“The farmers said their animals are more content, relaxed and calm when they interact with them in this way.

“Like our pets, farm animals are intelligent, sentient beings and respond well to positive interaction. As we communicate to animals, they communicate with us and actually tell us a lot about how they are feeling by the way they behave.

“This is about going back to basics and doing what good stock keepers do best: looking at and listening to their animals to measure how well they are.

“Of course, many farmers already do this and those on the RSPCA’s Freedom Food scheme work to a strict set of welfare standards. We are using science to develop a quick, simple set of measures to assess animal welfare.

“The results will help farmers see how well their animals are, better ­understand what they need and identify what more they can do to give them a really good life.”

Pig farmer Mark Hayward, of Woodbridge, Suffolk, regularly plays the harmonica to his pigs, while dairy farmer David Tory, from Dorset, says his cows know it’s only rock and roll, but they like it, particularly The Rolling Stones and Aerosmith.

He said: “A stressed cow won’t drop her milk, but we never have that problem with our girls.

“The secret to their happiness and good production is not only giving them the best care we can, but tuning into the local radio or Planet Rock.

“It makes them chilled out and that’s what produces great milk. As for chatting to our animals, we never stop.

“It helps us build a trusting relationship and makes us feel happy too.”